   (assoc ship :rotation-speed (+ rotation-speed rot)))
 
 (defn accelerate [{:keys [acceleration] :as ship} acc]
-  (assoc ship :acceleration (+ acceleration acc)))
+  (assoc ship :acceleration (+ acceleration acc)
+              :collidable? true))
 
 (defn toggle-shooting [ship do-shoot?]
-  (assoc ship :shooting? do-shoot?))
+  (assoc ship :shooting? do-shoot?
+              :collidable? true))
 
 ; ----------------------------------------------------------
 ; mutable model

   :rotation-speed         0

   :life                   ship-life
   })

(defn create-shot

    (if hit?
      (if (< fragment-size asteroid-min-size)
        nil
        (create-asteroids 3 fragment-size position speed))
      asteroid)))

(defn resolve-all-collision [{shots :shots :as ship} asteroids]
